Control device and control method for a fuel cell system

Abstract

This invention provides a control device and control method for a fuel cell system that enable further efficiency improvements (efficiency enhancement) of a 3-parallel boost converter. [Solution] The control unit 72 of the control device 15 of the fuel cell system 200 operates the centrally located boost converter 302 of the three parallel boost converters 300 in accordance with the power demand of the load, prioritizing its operation over the boost converters 301 and 303 located on either side of the centrally located boost converter 302.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a control apparatus for a fuel cell system including a fuel cell that generates electric power through an electrochemical reaction between two reaction gases, a fuel gas and an oxidant gas, and a control method thereof. BACKGROUND ART

[0002] In recent years, research and development on fuel cells (FCs) that contribute to energy efficiency improvement has been carried out to ensure that more people can access affordable, reliable, sustainable and advanced energy.

[0003] For example, Japanese Patent Laid-Open No. 2010-279135 (referred to as Patent Document 1) discloses a control apparatus for a multi-phase converter that determines the number of driven switching elements among a plurality of switching elements connected in parallel, according to the required power (required load) of a load electrically connected to a fuel cell.

[0004] Paragraphs

[0055] to

[0056] of Patent Document 1 describe that when the number of driven elements is 3 or more, the occurrence of thermal interference can be suppressed by determining the switching elements located inside the outermost switching elements on both sides as the switching elements not to be driven.

[0005] Further, paragraph

[0053] of Patent Document 1 also describes that by randomly selecting the driven phase and performing switching control, characteristic deterioration of the switching elements caused by partial use of the switching elements can be prevented in advance.

[0006] Further, for example, Japanese Patent Laid-Open No. 2009-163948 (referred to as Patent Document 2) discloses a fuel cell system including a three-phase converter.

[0007]

[0049] of Patent Document 2 describes using all three-phase converters under high load conditions. During low-boost, low-load conditions such as startup and shutdown, only boost converters with a wide boost ratio range capable of soft switching are used. Furthermore, when the load is moderate, two boost converters are used. It is disclosed that switching losses can be reduced by controlling the system in this way. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2010-279135 [Patent Document 2] Japanese Patent Publication No. 2009-163948 [Overview of the project] [Problems that the invention aims to solve]

[0009] This disclosure aims to provide a control device and control method for a fuel cell system that enable further efficiency improvements (efficiency enhancement) of a 3-parallel boost converter. [Means for solving the problem]

[0010] A control device for a fuel cell system according to one aspect of the present disclosure comprises a fuel cell that generates electricity using a supplied reaction gas, a three-parallel boost converter that boosts the generated voltage of the fuel cell, a load to which power is supplied from the three-parallel boost converter, and a control unit that controls the operation of the load and the three-parallel boost converter, wherein the three-parallel boost converter is integrally arranged in parallel on a circuit board between positive and negative input terminals and positive and negative output terminals, and the control unit operates the central phase boost converter, which is located in the center of the three-parallel boost converter, with priority given to the boost converters of the phases on either side of the central boost converter, according to the power demanded by the load.

[0011] A control method for a fuel cell system according to another aspect of the present disclosure is a control method for a fuel cell system having a fuel cell that generates electricity using a supplied reaction gas and a three-parallel boost converter that boosts the generated voltage of the fuel cell, wherein in single-phase operation only the central phase boost converter is operated, and in two-phase operation either the central phase or one of the phases on either side is operated. [Effects of the Invention]

[0012] According to this disclosure, it is possible to further improve the efficiency of the 3-parallel boost converter, which in turn contributes to energy efficiency. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic diagram of a fuel cell vehicle incorporating a fuel cell system equipped with a control device according to the embodiment. [Figure 2] Figure 2 is a circuit diagram of a 3-parallel boost converter module equipped with three parallel boost converters. [Figure 3] Figure 3 is a physical wiring diagram of a 3-parallel boost converter module equipped with 3 parallel boost converters. [Figure 4] Figure 4 is a schematic waveform diagram showing the step response of the central phase boost converter (dashed line) and the step response of the two-phase boost converters (solid lines). [Figure 5] Figure 5 is a schematic frequency response diagram showing the frequency characteristics of the central phase boost converter (dashed line) and the two-phase boost converters (solid lines). [Figure 6] Figure 6 is a table showing the contents of the boost converter determination map. [Figure 7] Figure 7 is a flowchart illustrating the operation of the control device according to this embodiment. [Modes for carrying out the invention]

[0014] [composition] FIG. 1 is a schematic configuration diagram of a fuel cell vehicle 202 in which a fuel cell system 200 including a control device 15 according to an embodiment is incorporated. The control device 15 executes the control method for the fuel cell system 200 according to the embodiment.

[0015] The fuel cell system 200 can also be incorporated into other moving bodies such as ships, aircraft, and robots other than the fuel cell vehicle 202, or buildings such as factory facilities.

[0016] The fuel cell vehicle 202 includes the fuel cell system 200, an electricity storage device system 201, a drive motor (load) 206 driven via an inverter (power conversion device) 204, and the control device 15 that controls the entire fuel cell vehicle 202.

[0017] The drive motor 206 is a motor generator, which serves as a load of the fuel cell system 200 during power running, and functions as a generator during regeneration.

[0018] The number of the control device 15 is not limited to one, and for example, two or more control devices such as one for the fuel cell system 200 and one for the drive motor 206 may be provided.

[0019] The fuel cell system 200 includes a fuel cell stack (also simply referred to as a fuel cell) 210, an oxidant gas supply device 212, a fuel gas supply device 214, a refrigerant supply device (not shown), and an electricity storage device 240.

[0020] The oxidant gas supply device 212 has a compressor (CP) 216 with adjustable impeller rotation speed, and an oxidant gas supply flow path 218. The compressor 216 supplies compressed outside air as an oxidant gas to the fuel cell 210 through the oxidant gas supply flow path 218.

[0021] The fuel gas supply device 214 includes a hydrogen tank (fuel gas storage device) 220, a fuel gas supply flow path 222, and a pressure regulating valve 224 provided in the fuel gas supply flow path 222.

[0022] The fuel gas supply device 214 reduces the pressure of the high-pressure fuel gas (hydrogen) stored in the hydrogen tank 220 via the pressure regulating valve 224, and supplies the reduced-pressure fuel gas to the fuel cell 210 through the fuel gas supply passage 222.

[0023] The fuel cell 210 generates electricity through the electrochemical reaction of the two supplied reaction gases (oxidizer gas and fuel gas), generating a powered voltage Vfc between the positive output terminal 226 and the negative output terminal 228, and supplying a powered current Ifc to the outside from the positive output terminal 226 and the negative output terminal 228. Here, the power generated Pfc of the fuel cell 210 is calculated as the product of the powered voltage Vfc and the powered current Ifc.

[0024] The fuel cell system 200 includes three parallel boost converter modules (also simply called boost modules) 100, which are electrically insulated and assembled on a flat aluminum plate with good heat dissipation.

[0025] The boost module 100 shown within the dashed-dotted frame includes an input terminal (positive input terminal) 10, an input terminal (negative input terminal) 11, an output terminal (positive output terminal) 50, and an output terminal (negative output terminal) 51. The negative input terminal 11 and the negative output terminal 51 can also be considered to function as ground terminals electrically.

[0026] The boost module 100 comprises an inductor (common-mode coil) L including inductors L1, L2, and L3, switching modules 101 to 103, smoothing capacitors C1 to C3, and a ring-shaped ferrite core 48.

[0027] Figure 2 shows a circuit diagram of a 3-parallel boost converter module 100, which includes 3 parallel boost converters 300.

[0028] As shown in Figure 2, the switching modules 101, 102, and 103 each comprise switching elements Q1, Q2, and Q3, which have reverse diodes Da, Db, and Dc connected in parallel, and diodes (rectifier diodes) D1, D2, and D3, respectively.

[0029] Figure 3 is a wiring diagram of a 3-parallel boost converter module 100 equipped with 3 parallel boost converters 300. As shown in Figure 3, the 3-parallel boost converters 300 are arranged on a substrate 90 made of an aluminum plate and are integrally mounted on the substrate 90. That is, the 3-parallel boost converters 300 are integrally arranged in parallel on the substrate 90 between the positive input terminal 10 and the negative input terminal 11 and the positive output terminal 50 and the negative output terminal 51.

[0030] As shown in Figure 1, the positive input terminal 10 is connected to the positive output terminal 226 of the fuel cell 210 via the positive busbar 231. The negative input terminal 11 is connected to the negative output terminal 228 of the fuel cell 210 via the negative busbar 232.

[0031] The positive busbar 231 and the negative busbar 232 are each made of thick copper plates (busbars). The positive busbar 231 and the negative busbar 232 may also be made of thick electric wires (copper wires). In this disclosure, the electric wires and busbars are basically interchangeable.

[0032] The positive output terminal 50 of the 3-parallel boost converter module 100 shown in Figure 3 is connected to the positive terminal of the inverter 204 via the electric wire (busbar) 241 (Figure 1). The negative output terminal 51 of the 3-parallel boost converter module 100 is connected to the negative terminal of the inverter 204 via the electric wire (busbar) 242 (Figure 1).

[0033] As shown in Figure 3, the 3-parallel boost converter module 100 has a 3-parallel boost converter (SUC) 300, which comprises a central phase boost converter 302 located in the center, and outer phase boost converters 301 and 303 located on both sides of the central phase boost converter 302.

[0034] The 3-parallel boost converter 300 boosts the generated voltage Vfc (Figure 1) applied between the positive input terminal 10 and the negative input terminal 11, and applies the boosted voltage between the positive output terminal 50 and the negative output terminal 51.

[0035] As shown in Figure 1, a boosted voltage of the generated voltage Vfc is applied to the DC input terminal of the inverter 204 from the 3-parallel boost converter module 100 as the DC terminal voltage Vinv.

[0036] The fuel cell system 200 further includes an energy storage device 240 such as a lithium-ion secondary battery. The energy storage device 240 generates an energy storage voltage Vb between the positive terminal and the negative terminal.

[0037] The positive terminal of the energy storage device 240 is connected to the low-voltage positive terminal of the buck-boost converter (SUDC) 248 via a wire (busbar) 243. The negative terminal of the energy storage device 240 is connected to the low-voltage negative terminal of the buck-boost converter 248 via a wire (busbar) 244.

[0038] The high-voltage positive terminal of the buck-boost converter 248 is connected to wire 241 via wire (busbar) 245. The high-voltage negative terminal of the buck-boost converter 248 is connected to wire 242 via wire (busbar) 246.

[0039] When the drive motor 206 is operating, the step-up / step-down converter 248 boosts the stored voltage Vb of the energy storage device 240 and applies the boosted voltage as a DC terminal voltage Vinv to the DC terminal of the inverter 204.

[0040] This DC terminal voltage Vinv is converted into a three-phase AC voltage by the inverter 204 to drive the drive motor 206. As a result, the fuel cell vehicle 202 moves.

[0041] On the other hand, the three-phase AC voltage generated in the drive motor 206 during regeneration, such as when driving downhill, is converted to a DC end voltage (DC link voltage) Vinv by the inverter 204. This DC end voltage Vinv is stepped down to a storage voltage Vb by the step-up / step-down converter 248 and applied to the energy storage device 240 to charge the energy storage device 240.

[0042] The generated voltage Vfc, which constitutes the surplus generated power Pfc of the fuel cell 210, is boosted by a 3-parallel boost converter 300. This boosted voltage is stepped down to a storage voltage Vb by a buck-boost converter 248 and applied to the energy storage device 240 to charge the energy storage device 240.

[0043] As shown in Figures 2 and 3, the parallel-connected boost converters 301 to 303 are equipped with, in order from the positive input terminal 10 and negative input terminal 11 side, inductors L (inductors L1, L2, L3) which are choke coils and in-phase coils, three parallel switching modules 101, 102, and 103, smoothing capacitors C1, C2, C3, and a ferrite core 48 between the positive input terminal 10 and negative input terminal 11 and the positive output terminal 50 and negative output terminal 51. A positive busbar (positive output wiring) 21 and a negative busbar (negative output wiring) 16 pass through the ferrite core 48. The inductors L are configured with thick wires wound around a ring core.

[0044] As shown in Figure 2, the three parallel switching modules 101 to 103 are each provided with switching elements Q1, Q2, and Q3 between the positive and negative busbars (20 and 16, 30 and 16, and 40 and 16), respectively. Reverse diodes Da, Db, and Dc are connected in parallel to the switching elements Q1, Q2, and Q3, respectively. The anode terminals of the output diodes D1, D2, and D3 are connected to the positive busbars 20, 30, and 40, respectively. The cathode terminals of the output diodes D1, D2, and D3 are connected to the common positive busbar 21. Smoothing capacitors C1, C2, and C3 are connected between the positive busbar 21 and the negative busbar 16.

[0045] The smoothing capacitors C1, C2, and C3 may each be divided into two smoothing capacitors, resulting in a total of six smoothing capacitors. While the smoothing capacitors C1, C2, and C3 each have the same capacitance, it is also possible to have only one smoothing capacitor C2 with three times the capacitance. As will be described later, the capacitance of the central phase smoothing capacitor C2, which operates most frequently, may be made larger than the capacitances of the smoothing capacitors C1 and C3 on either side of it.

[0046] In Figure 3, the negative electrode busbar 16 of a single component manufactured by integral molding has numerous dots drawn on it for ease of understanding.

[0047] As shown in Figures 2 and 3, the positive input terminal 10 is provided at one end of a common positive busbar 14, the other end of the positive busbar 14 is connected to one end of an inductor L(L1, L2, L3), and the other end of the inductor L(L1, L2, L3) is connected to one end of positive busbars 20, 30, and 40.

[0048] The other ends of the positive busbars 20, 30, and 40 extend in the X direction in Figure 3, supporting the switching modules 101 to 103, and further extending in the X direction, where they are connected to the anode terminals of the output diodes D1 to D3, respectively, within the switching modules 101 to 103.

[0049] The cathode terminal of output diode D1 is connected to one end of a positive busbar 21 extending in the X direction. The positive busbar 21, connected to the cathode terminal of output diode D1 and extending in the X direction, bends 90° and extends in the -Y direction, where it merges at a confluence (connection) 21b.

[0050] A positive busbar 21, with one end connected to the cathode terminal of output diode D2, extends in the X direction and merges at the junction 21b.

[0051] The cathode terminal of output diode D3 is connected to one end of a positive busbar 21 extending in the X direction. The positive busbar 21, connected to the cathode terminal of output diode D3 and extending in the X direction, bends 90° and extends in the Y direction, where it merges at a confluence (connection) 21b.

[0052] The positive busbar 21 extends in the X direction from the junction (connection) 21b, passes through the ferrite core 48, and is connected to the positive output terminal 50.

[0053] Therefore, the length of the positive busbar 21 of the central phase boost converter 302 is shorter than the length of the positive busbar 21 of the outer phase boost converters 301 and 303 on both sides, which have bent sections, thus reducing the stray inductance.

[0054] The negative input terminal 11 is connected to the negative busbar 16, which extends in the X direction, passes through the junction (connection) 16a, and further extends in the X direction to become the negative busbar 16 of the central phase switching module 102, and from this negative busbar 16 it extends further in the X direction to the junction (connection) 16b, and further extends from the junction (connection) 16b it extends in the X direction to the negative output terminal 51.

[0055] The negative electrode busbar 16 extends at the junction (connection) 16a, bending 90° in the Y and -Y directions, then bending 90° in the X direction and extending in the X direction, supporting the switching modules 101 and 103 on both sides, extending in the X direction as the negative electrode busbar 16, then bending 90° again in the Y and -Y directions and extending until it merges at the junction (connection) 16b. The negative electrode busbar 16 extends further in the X direction from the junction (connection) 16b, passes through the ferrite core 48, and is connected to the negative output terminal 51.

[0056] The length of the negative electrode busbar 16 from the negative input terminal 11, passing under the central switching module 102, through the junction (connection) 16b, and reaching the negative output terminal 51 is shorter than the length of the negative electrode busbar 16 that bends from the negative input terminal 11, passes under the switching modules 101 and 103 on both sides, bends again, reaches the junction (connection) 16b, and reaches the negative output terminal 51. Therefore, the stray inductance is reduced.

[0057] The switching modules 101-103 and the negative busbar 16, and the positive busbars 20, 30, 40, and 21 are fixed onto the substrate 90 by insert molding. The substrate 90 is made of die-cast aluminum.

[0058] [Transient response of a boost converter] Here, the transient response of boost converters 301-303 will be explained with reference to Figures 4 and 5.

[0059] Figure 4 is a schematic waveform diagram showing the step response (transient response) of the parallel-connected boost converters 301 to 303. The step response waveform 82, shown by the dashed line for the central phase boost converter 302, has a smoother rise time and less distortion compared to the step response waveforms 80, shown by the solid lines for the boost converters 301 and 303 on either side.

[0060] The step response waveform 82 shows a smaller surge voltage compared to the step response waveform 80, thus enabling improved efficiency. The step response waveform 80, shown by the solid line, has ringing at the rising edge and is a distorted waveform.

[0061] The reason for the difference between step response waveform 80 and step response waveform 82 is presumed to be mainly due to the amount of stray inductance. The step response waveform 80 of boost converters 301 and 303, which have long wiring lengths and large stray inductance, shows greater ringing compared to boost converter 302, which has small stray inductance.

[0062] Figure 5 is a schematic frequency response diagram showing the frequency characteristics of boost converters 301 to 303. The frequency response 182 of the central phase boost converter 302, shown by the dashed line, shows a more gradual decrease with increasing frequency compared to the frequency responses 180 of the two phase boost converters 301 and 303, shown by the solid lines. The horizontal axis is logarithmic.

[0063] The frequency response singularity 180p corresponds to the fundamental frequency of the ringing frequency. The high-frequency singularities 180q and 182q correspond to frequencies that are integer multiples of the ringing frequency. It has been confirmed that the high-frequency singularities 180q and 182q can be reduced by inserting the ferrite core 48.

[0064] The central phase boost converter 302, which exhibits smooth step and frequency responses, has been confirmed to have low EMC (Electromagnetic Compatibility) noise. The switching loss of the central phase boost converter 302 is smaller compared to the switching losses of the outer boost converters 301 and 303 on both sides.

[0065] The inventors of this application have found that the following phenomena exist in the technology relating to fuel cell systems using three parallel boost converters.

[0066] Firstly, the transient response of the three parallel boost converters arranged on the circuit board differs due to differences in signal wiring, ground wiring, and thus differences in stray inductance among the converters.

[0067] Secondly, due to the difference (superiority) in transient response, the power loss of each converter differs in a three-parallel boost converter.

[0068] Thirdly, due to the difference in transient response, the 3-parallel boost converters have different EMI (Electromagnetic Interference) characteristics. This disclosure provides superior technology that takes the above-mentioned phenomena into consideration.

[0069] [Control device] Next, the control device 15 will be described. The control device 15 is a computer installed in the fuel cell system 200.

[0070] As shown in Figure 1, the control device 15 includes an arithmetic unit 70 and a storage unit 76. The control device 15 further includes peripheral devices (not shown), a display unit, and an operation unit.

[0071] The arithmetic unit 70 may be composed of a processor such as a CPU or GPU. That is, the arithmetic unit 70 may be composed of processing circuits. The arithmetic unit 70 includes a determination unit 74 and a control unit 72. The determination unit 74 and the control unit 72 may be realized by the execution of a program recorded in the storage unit 76 by the arithmetic unit 70.

[0072] Furthermore, at least a portion of the determination unit 74 and the control unit 72 may be implemented using integrated circuits such as ASICs and FPGAs. Also, at least a portion of the determination unit 74 and the control unit 72 may be composed of electronic circuits including discrete devices.

[0073] The storage unit 76 may consist of volatile memory and non-volatile memory. Examples of volatile memory include RAM. This volatile memory is used as the working memory of the processor and temporarily stores data necessary for processing or calculation. Examples of non-volatile memory include ROM and flash memory. This non-volatile memory is used as storage memory and stores programs, tables, maps, etc. At least a part of the storage unit 76 may be provided in the processor, integrated circuit, etc. as described above. In this embodiment, the boost converter determination map 78 is recorded in the storage unit 76.

[0074] Figure 6 is a table showing the contents of the boost converter decision map 78. The boost converter decision map 78 decides to activate the central phase boost converter 302 when the load request power Preq is less than or equal to the first power threshold P1 (Preq ≤ P1).

[0075] If the load power request Preq exceeds the first power threshold P1 (Preq>P1) but is less than or equal to the second power threshold P2 (Preq≦P2), it is decided to activate the central phase boost converter 302 and also activate one of the boost converters 301 or 303 on either side of the phases. The choice of which boost converter 301 or 303 to activate is determined so that their cumulative operating times are equal.

[0076] If the load power request Preq exceeds the second power threshold P2 (Preq > P2) but is less than or equal to the third power threshold P3 (Preq ≤ P3), it is decided to activate all three phase boost converters 301, 302, and 303.

[0077] [Operation] Next, the operation of the control device 15 of the fuel cell system 200, which is basically configured as described above, and the procedure for controlling it will be explained in detail based on the flowchart shown in Figure 7.

[0078] In step S1, the control unit 72 detects the load power request Preq and proceeds to step S2. Here, the load power request Preq is the total power consumption of the power supplied to the drive motor 206 (main motor) according to the amount of accelerator pedal operation, and the auxiliary power required for auxiliary equipment such as the compressor 216. Based on the load power request Preq and the State of Charge (SOC) of the energy storage device 240, the distribution of this total power consumption is determined to be covered by the power generated by the fuel cell 210 Pfc and the energy stored in the energy storage device 240 Pbat.

[0079] In step S2, the determination unit 74 determines whether the load request power Preq is less than or equal to the first power threshold P1. If the determination is positive (S2: YES), the control unit 72 proceeds to step S3.

[0080] In step S3, the control unit 72 activates only the central phase boost converter 302 and terminates the current process. In this step S3 process, the control unit 72 stops the operation of the switching elements Q1 and Q3 of the boost converters 301 and 303 on both sides and keeps them in the off state. In this case, the control unit 72 determines the DC terminal voltage Vinv according to the load power request Preq, determines the duty cycle of the boost converter 302 and activates the switching module 102. If there is sufficient SOC, the switching elements of the buck-boost converter 248 are also activated.

[0081] In this way, when the load required power Preq is equal to or less than the first power threshold P1, by operating only the boost converter 302 of the central phase among the boost converters 301 to 303 connected in parallel, the fuel cell system 200 can be operated with improved power conversion efficiency and reduced EMC.

[0082] If the determination in step S2 is a negative determination (S2: NO) (Preq>P1), the determination unit 74 further determines in step S4 whether the load required power Preq is equal to or less than the second power threshold P2.

[0083] If the determination in step S4 is a negative determination (S4: NO) (Preq>P2), the control unit 72 advances the process to step S5.

[0084] In step S5, the control unit 72 operates all (all phases) of the boost converters 301 to 303 connected in parallel and, as necessary, the buck-boost converter 248, to drive the drive motor 206.

[0085] If the determination in step S4 is an affirmative determination (S4: YES) (P1<Preq≦P2), the control unit 72 advances the process to step S6.

[0086] In step S6, the control unit 72 operates the boost converter 302 of the central phase, and operates either one of the boost converters 301 and 303 of the phases on both sides.

[0087] As a result, during this two-phase operation, ringing in transient response is reduced compared to the case where the boost converters 301 and 303 of the phases on both sides are operated as the boost converters for two phases. As a result, electromagnetic interference and the like are reduced, and EMI characteristics are improved. At the same time, since power loss caused by ringing can be reduced, operation with excellent power conversion efficiency can be performed.

[0088] According to the above embodiment, among the boost converters 301 to 303 connected in parallel, the central phase boost converter 302, which is located in the middle, has high switching efficiency because ringing is suppressed. By preferentially operating this central phase boost converter 302, the switching efficiency of the parallel-connected boost converters 301 to 303 from the low output region to the high output region can be increased.

[0089] Furthermore, the ringing frequency of the central phase boost converter 302, which is located in the center, is shifted from the ringing frequencies of the two phase boost converters 301 and 303, which are located on either side. Therefore, by preferentially operating the central phase boost converter 302, transient response ringing is reduced. This improves EMI characteristics. At the same time, since power loss due to ringing is reduced, operation with excellent power conversion efficiency can be achieved.

[0090] [Differentiation] The above-described embodiment can also be modified as follows. <Variation> In the above embodiment, in a plan view, among the boost converters 301 to 303 arranged in parallel, the central phase boost converter 302, which has a small stray inductance, is preferentially operated.

[0091] However, in the implementation configuration, if the stray inductance of one of the boost converters located on one side is smaller than the stray inductance of the boost converters on the other side and the central phase, the boost converter on either side with the smaller stray inductance may be given priority in operation.

[0092] [Note] In addition to the disclosures mentioned above, the following further notes are made:

[0093] (Note 1) The control device (15) for the fuel cell system (200) comprises a fuel cell (210) that generates electricity using a supplied reaction gas, three parallel boost converters (300 (301~303)) that boost the generated voltage (Vfc) of the fuel cell, a load (206) to which power is supplied from the three parallel boost converters, and a control unit (72) that controls the operation of the load and the three parallel boost converters. The three parallel boost converters are integrally arranged in parallel on a circuit board (90) between positive and negative input terminals (10, 11) and positive and negative output terminals (50, 51). The control unit operates the centrally located boost converter (302) of the three parallel boost converters with priority over the boost converters (301, 303) located on either side of the centrally located boost converter, according to the power requirements of the load.

[0094] This configuration allows for further efficiency improvements in the three-parallel boost converter, ultimately contributing to energy efficiency. More specifically, the centrally located boost converter has high switching efficiency. By prioritizing the operation of this centrally located boost converter, the switching efficiency of the three-parallel boost converter can be increased. Furthermore, the ringing frequency of the centrally located boost converter is shifted from the ringing frequencies of the boost converters on either side. Therefore, prioritizing the operation of the centrally located boost converter reduces transient response ringing. This improves EMI characteristics. At the same time, since power loss due to ringing is reduced, operation with superior power conversion efficiency is possible.

[0095] (Note 2) In the control device for the fuel cell system described in Appendix 1, if the control unit prioritizes the operation of the central phase boost converter over the boost converters of the phases on either side, it may operate only the central phase boost converter in single-phase operation, and operate the central phase boost converter and one of the boost converters of the phases on either side in two-phase operation. According to this, transient ringing is reduced during single-phase and two-phase operation, resulting in less electromagnetic interference and improved EMI characteristics. At the same time, power loss due to ringing is reduced, enabling operation with superior power conversion efficiency.

[0096] (Note 3) In the control device for the fuel cell system described in Appendix 1, the control unit may operate the boost converter in the following order as the power requirement of the load increases: only the central phase, the central phase and either of the phases on either side, and then all three phases. According to this, the average system efficiency of a fuel cell system can be improved by operating the optimal number of boost converters according to the power requirements of the load.

[0097] (Note 4) In the control device for the fuel cell system described in Appendix 1, each of the three parallel boost converters is equipped with an output diode (D1, D2, D3), and the connection distance from the cathode terminal of the central phase output diode (D2) to the positive output terminal (50) of the positive and negative output terminals may be shorter than the connection distance from the cathode terminals of the output diodes (D1, D3) on either side to the positive output terminals. According to this, the connection distance from the central phase output diode to the positive output terminal is minimized, so the stray inductance proportional to this connection distance is minimized, and the ringing in the transient response of the central layer boost converter can be made smaller than the ringing of the boost converters on both sides.

[0098] (Note 5) In the control device for the fuel cell system described in Appendix 4, the three parallel boost converters have smoothing capacitors (C1, C2, C3), and the smoothing capacitors may consist of at least three smoothing capacitors. According to this method, the output current of each phase of the three-phase boost converter can charge each capacitor via the shortest possible path, thus reducing ringing.

[0099] (Note 6) In the control device for the fuel cell system described in Appendix 4, a ferrite core (48) may be provided through which a positive output wire (21), one end of which is connected to the cathode terminal of the output diode and the other end of which is connected to the positive output terminal, and a negative output wire (16), one end of which is connected to the negative input terminal and the other end of which is connected to the negative output terminal, each pass. According to this, high-frequency ringing can be further suppressed by the high-frequency loss of the ferrite core.

[0100] (Note 7) The fuel cell system control method is a method for controlling a fuel cell system having a fuel cell that generates electricity using a supplied reaction gas and a 3-parallel boost converter that boosts the generated voltage of the fuel cell, wherein in single-phase operation only the central phase boost converter is operated, and in two-phase operation the central phase and one of the boost converters of either of the phases on either side are operated.

[0101] This allows for further efficiency improvements in the 3-parallel boost converter, ultimately contributing to improved energy efficiency. In both single-phase and two-phase operation, transient ringing is reduced, resulting in less electromagnetic interference and improved EMI characteristics. Simultaneously, power loss due to ringing is reduced, enabling operation with superior power conversion efficiency.

[0102] This disclosure is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of Symbols]

[0103] 15...Control device 72...Control unit 74...Judgment section 76...Storage section 78…Boost Converter Determination Map 100... Boost module (3 parallel boost converter module) 101-103... Switching Modules 300...3 parallel boost converters 301~303...boost converters C1-C3: Smoothing capacitors D1-D3: Output diodes

Claims

1. A fuel cell that generates electricity using the supplied reaction gas, A three-parallel boost converter for boosting the power generated by the fuel cell, A load to which power is supplied from the three parallel boost converters, The load and the control unit that controls the operation of the three parallel boost converters, A control device for a fuel cell system comprising: The three parallel boost converters are integrally arranged in parallel on the circuit board between the positive and negative input terminals and the positive and negative output terminals. The control unit, In accordance with the power requirements of the load, the central phase boost converter, located in the center of the three parallel boost converters, is operated with priority over the boost converters on either side of the central phase converter. Control device for a fuel cell system.

2. In the control device for the fuel cell system according to claim 1, The control unit, When the boost converter of the central phase is to be operated preferentially over the boost converters of the phases on both sides, In single-phase operation, only the boost converter of the central phase is operated, and in two-phase operation, the boost converter of the central phase and the boost converter of either of the two phases are operated. Control device for a fuel cell system.

3. In the control device for the fuel cell system according to claim 1, The control unit, As the power requirement of the load increases, the boost converters are operated in the following order: only the central phase, the central phase and either of the phases on either side, and then all three phases. Control device for a fuel cell system.

4. In the control device for the fuel cell system according to claim 1, Each of the parallel-connected boost converters is equipped with an output diode, and the connection distance from the cathode terminal of the central phase output diode to the positive output terminal of the positive and negative output terminals is shorter than the connection distance from the cathode terminal of the output diodes of the two side phases to the positive output terminals. Control device for a fuel cell system.

5. In the control device for the fuel cell system according to claim 4, The aforementioned three parallel boost converters include smoothing capacitors, and these smoothing capacitors are composed of at least three smoothing capacitors. Control device for a fuel cell system.

6. In the control device for the fuel cell system according to claim 4, The device includes a ferrite core through which a positive output wire, one end of which is connected to the cathode terminal of the output diode and the other end of which is connected to the positive output terminal, and a negative output wire, one end of which is connected to the negative input terminal and the other end of which is connected to the negative output terminal, passes. Control device for a fuel cell system.

7. A fuel cell that generates electricity using the supplied reaction gas, A control method for a fuel cell system having three parallel boost converters for boosting the generated voltage of the fuel cell, In single-phase operation, only the central phase boost converter is activated, while in two-phase operation, the central phase and one of the phases on either side are activated. A method for controlling a fuel cell system.

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